From 1a2654d291e530a189c376702d6f47ecc05c84bc Mon Sep 17 00:00:00 2001
From: Mike Griese <migrie@microsoft.com>
Date: Mon, 13 Jan 2020 17:07:43 -0600
Subject: [PATCH] Try to wrap the line properly with conpty

  This confusingly doesn't always work
---
 src/renderer/vt/XtermEngine.cpp | 13 +++++++++++--
 src/renderer/vt/paint.cpp       | 15 +++++++++++++++
 src/renderer/vt/vtrenderer.hpp  |  2 ++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/renderer/vt/XtermEngine.cpp b/src/renderer/vt/XtermEngine.cpp
index 2c1d8a08ed1..556381c5661 100644
--- a/src/renderer/vt/XtermEngine.cpp
+++ b/src/renderer/vt/XtermEngine.cpp
@@ -19,7 +19,7 @@ XtermEngine::XtermEngine(_In_ wil::unique_hfile hPipe,
     _ColorTable(ColorTable),
     _cColorTable(cColorTable),
     _fUseAsciiOnly(fUseAsciiOnly),
-    _previousLineWrapped(false),
+    // _previousLineWrapped(false),
     _usingUnderLine(false),
     _needToDisableCursor(false),
     _lastCursorIsVisible(false),
@@ -248,7 +248,13 @@ XtermEngine::XtermEngine(_In_ wil::unique_hfile hPipe,
 
             // If the previous line wrapped, then the cursor is already at this
             //      position, we just don't know it yet. Don't emit anything.
-            if (_previousLineWrapped)
+            bool previousLineWrapped = false;
+            if (_wrappedRow.has_value())
+            {
+                previousLineWrapped = coord.Y == _wrappedRow.value() + 1;
+            }
+
+            if (previousLineWrapped)
             {
                 hr = S_OK;
             }
@@ -298,6 +304,9 @@ XtermEngine::XtermEngine(_In_ wil::unique_hfile hPipe,
         _newBottomLine = false;
     }
     _deferredCursorPos = INVALID_COORDS;
+
+    _wrappedRow = std::nullopt;
+
     return hr;
 }
 
diff --git a/src/renderer/vt/paint.cpp b/src/renderer/vt/paint.cpp
index 920dc86aeb2..02b35895968 100644
--- a/src/renderer/vt/paint.cpp
+++ b/src/renderer/vt/paint.cpp
@@ -449,6 +449,21 @@ using namespace Microsoft::Console::Types;
     std::wstring wstr = std::wstring(unclusteredString.data(), cchActual);
     RETURN_IF_FAILED(VtEngine::_WriteTerminalUtf8(wstr));
 
+    // If we've written text to the last column of the viewport, then mark
+    // that we've wrapped this line. The next time we attempt to move the
+    // cursor, if we're trying to move it to the start of the next line,
+    // we'll remember that this line was wrapped, and not manually break the
+    // line.
+    // Don't do this is the last character we're writing is a space - The last
+    // char will always be a space, but if we see that, we shouldn't wrap.
+
+    // TODO: This seems to be off by one char. Resizing cmd.exe, the '.' at the
+    // end of the initial message sometimes gets cut off weirdly.
+    if ((_lastText.X + (totalWidth - numSpaces)) > _lastViewport.RightInclusive())
+    {
+        _wrappedRow = coord.Y;
+    }
+
     // Update our internal tracker of the cursor's position.
     // See MSFT:20266233
     // If the cursor is at the rightmost column of the terminal, and we write a
diff --git a/src/renderer/vt/vtrenderer.hpp b/src/renderer/vt/vtrenderer.hpp
index 5adf1cd1d9c..3b180e5e7c7 100644
--- a/src/renderer/vt/vtrenderer.hpp
+++ b/src/renderer/vt/vtrenderer.hpp
@@ -136,6 +136,8 @@ namespace Microsoft::Console::Render
         Microsoft::Console::VirtualTerminal::RenderTracing _trace;
         bool _inResizeRequest{ false };
 
+        std::optional<short> _wrappedRow{ std::nullopt };
+
         [[nodiscard]] HRESULT _Write(std::string_view const str) noexcept;
         [[nodiscard]] HRESULT _WriteFormattedString(const std::string* const pFormat, ...) noexcept;
         [[nodiscard]] HRESULT _Flush() noexcept;